The 3rd Generation Partnership Project (3GPP) Long Term Evolution-Advance Rel-10/11 (LTE-A Rel-10/11) is an enhancement of LTE Rel-8 technology. An LTE-A system has a higher bandwidth requirement than an LTE system, and supports a peak data rate up to 1 Gbits/s. In order to meet the bandwidth requirement of LTE-A, the LTE-A system uses a Carrier Aggregation (CA) technology as a method for expanding system bandwidth, and extensively adopts a Multiple Input Multiple Output (MIMO) enhancement technology (also referred to as a multi-antenna technology) and an adaptive technology to improve data rate and system performance.
Although the LTE-A adopts a variety of technologies to improve data rate, with rapid development of wireless communications and the emergence of super high rate services (such as high-definition video), loads on a wireless communication network have become heavier and heavier. Reducing network load has become a hot research topic, which has promoted emergence of D2D communication. D2D communication is quite likely to become a major project of LTE-A Rel-12. In D2D communication mode, two terminals may communicate directly without forwarding of a base station, thereby sharing data load of the base station. Since there is only one hop in the D2D communication, no intermediate device is needed, thereby better utilizing spectral resources, improving spectral efficiency and data transmission rate, and alleviating burden of the base station.
In order to improve spectral efficiency and to more fully utilize the radio frequency capabilities of an existing terminal, a D2D communication link shares spectral resources with an existing mobile communication network. In order to not interfere with a terminal of the existing network, D2D communication does not use downlink spectral resources (i.e., a link from an eNB to a UE) of the LTE-A, and only multiplexes uplink spectral resources (i.e., a link from a UE to an eNB) of the LTE-A, as a base station has much better anti-interference capability than a common User Equipment (UE). It has a relatively larger probability that two D2D devices time division multiplex on the uplink spectral resource, therefore, it is not necessary to support simultaneously receiving and sending, and one device can just receive while another device is sending.